Control mechanism



Feb. 14, 1939. D, TAYLOR 2,147,274

CONTROL MECHANISM Filed Feb. 28, 1936 Fig.1

//YV/V TOE Daniel G. TayZofi 8) ATTOENEY Patented Feb. 14, 1939- UNITED STATES PATENT OFFICE CONTROL DIECHANISM Application February 28, 1936, Serial No. 66,215

4 Claims.

This invention relates to control mechanism and more particularly to that type of device adapted to control a source, or a plurality of sources, of heat through the actuation of a ther- 5 mostatic element.

One object of this invention is the provision, in a single controlunit, of a proportioning control mechanism and a make and break contact switching mechanism actuated by a single ther- 10 mally responsive element.

Another object is the provision of an improved thermostat including a proportioning control comprising an arm adapted to travel over a resistance element and an open contact switching 15 mechanism actuated by the movement of the arm.

A further object is the provision of such a mechanism as described in the preceding paragraph wherein the open contact switch is actu- 90 ated by the proportioning control arm at, or near,

one limit of its range of movement.

A further object is the provision of a control system for heat regulation comprising a thermostat adapted to regulate, through a potentiometer coil, a proportioning heating device such as a unit ventilator, and through a two position switching mechanism, a second heating device such as a conventional radiator.

A more specific object is the provision of a 1:0 control system adapted to actuate, from a single thermostatic element, such mechanism as a unit ventilator and a conventional radiator, the arrangement being suchthat when the full heat radiating capacity of the unit ventilator is required, the radiator maybe actuated to supplement the amount of heat provided to the space which it is desired to heat.

As conducive to a clearer understanding of the invention, it may here be pointed out that in w the arrangement of heating systems adapted for various uses it is sometimes desirable to provide a conventional heating equipment which may be comprised of radiators supplied with steam from a central heating plant and also, in the same .13 space, to provide unit ventilating mechanism. Such unit ventilating mechanism may take the form of a ventilator device provided with dampers to control the admission of air from a source exterior of the building or room, the tempera- .50 ture of which it is desired to control, and also provided with means to heatthe air so ad mitted, which may comprise steam coils supplied with steam from the same central source of heat referred to above.

55 Under normal circumstances, the unit ventilator supplies all necessary heat. It will sometimes happen, however, that the heating capacity of the unit ventilator is insufficient, under abnormal conditions, such as unusually cold weather, to maintain the temperature at the desired level. Under such circumstances, it is desirable that the heating capacity of the unit ventilator'be supplemented by that of the radiator. There has hitherto been experienced considerable difficulty in providing a control mechanism which would regulate and proportion the amount of heat supplied by the unit ventilator, to the temperature conditions maintained withn the space to be heated and which would also, upon a requirement for more heat, automatically supply such heat from auxiliary heating means: as might be comprised of conventional steam radiators.

One object of this invention is the provision of a mechanism which will obviate the above difliculties in an efiicient and satisfactory manner.

Other objects will in part be obvious and in part pointed out hereinafter.

Accordingly, the invention consists in the combinations of elements, arrangements of parts, and features of construction all as will be hereinafter pointed out and shown in the accompanying drawing and the scope of the application of which will be indicated in the appended claims.

Referring now to the drawing:

Figure 1 is a front elevational view of a structure embodying the features of the instant invention;

Figure 2 is a schematic showing partially in perspective of one of the various applications of the structure of the instant invention to a control system, and

Figure 3 is a sectional View taken along the line 33 of Figure 2.

Similar reference characters designate similar parts throughout the several views of the draw- 111g.

Referring now to the drawing and more particularly to Figure 1, there is generally indicated at l an insulating panel to which is secured, in any desired manner, a bracket l. A volatile fluid bellows l2 having an extending projection I3 is secured to and carried by bracket II. Projection l3 abuts a suitable indentation M in a bell-crank lcvez' l5. Lever l5 has a ccncavo-convex portion l6 which pivotally engages a knife edge ll carried by a suitable supporting member l8., One end of lever l5 has passed therethrough a screw 69 having a head 20 which serves to hold the same normally juxtaposed to lever I5. Screw I9 threadedly engages a suitable threaded aperture in a plate 2| rigidly secured to the bottom of a spring 22. An indicating arm 23 is rigidly secured to the opposite end of spring 22 which engages a threaded member 24 having an extending head 25. A scale plate 26 bearing indicia is mounted adjacent indicating arm 23 on a suitable bracket, a fragment of which is shown at 21. Also mountedon bracket 21 and extending laterally therefrom is a resistance element 29 which may take the form of a conventional potentiometer having a coil 30. An insulating housing 28 surrounds coil 30. Wires SI and 32 lead from the opposite ends of coil 30 to appropriate terminals 33 and 36 respectively carried by panel II].

The end of lever I5 opposite screw I9 has mounted thereon, as by means of suitable screws 35, a leaf spring 36 which has a contact finger 31 secured to an extremity in any desired manner, as by soldering. Finger 31 is so arranged as to be juxtaposed to potentiometer coil 30 and held in Contact therewith by the action of spring 36. Suitable insulating washers 38, as better shown in Figure 3, are positionedabout screws 35 between lever I5 and spring member 36 in order to electrically insulate spring 36 from lever I5 and its associated parts. A wire 39 extends from a suitable junction 40 with spring 36 to an appropriate terminal 6! carried by insulating panel II).

From the above it will now be seen that the temperature in the space wherein is mounted the instrument will, upon fluctuation, vary the pressure within bellows I2, which movement will in turn be imparted through projection I3 and indentation I4 to lever I5. One end of lever I5 being held substantially fixed by the pull of spring 22, the opposite end, which carries leaf spring 36 and finger 31, will be moved to vary the position of contact finger 31 with respect to potentiometer coil 30. The operation of this proportioning mechanism which comprises a conventional potentiometer is well known and need not be described here.

It will further be seen that by adjustment of head 25, the tension of spring 22 may be varied in order that contact finger 31 may assume a different position with respect to coil 30 at difierent temperature values. Screw I 9 provides suitable means whereby the instrument may be calibrated at the factory to predetermine these temperature values. The indicia, previously referred to, carried by scale plate 26 may, accordingly, take the form of temperature value indications in degrees.

Lever l5 has an extending portion 50 which has mounted thereon an abutment member 5I. As better 'shown in Figure 2, member 5| comprises an upwardly extending portion 52, secured to portion 56 of lever I5 by screws 53 and insulated therefrom by suitable insulating washers 56, an inwardly extending portion 55 and a second upwardlyextending portion 56. Mounted adjacent portion 56 upon a pivot pin 51 is a bracket 58 which bears an extending member 59 shaped to form an abutment 60, and a leaf spring contact 6| having contact buttons 62 and Men opposite sides thereof. The arrangement is such that abutment 60 is juxtaposed to upwardly extendingportion 56 of bell crank member 5|. Mounted adjacent contact buttons 62 and 63 are posts 64 and 65 hearing contact screws 66 and 61, respectively. Wires 66 and69 lead respectively from contact posts 64 and 65 to terminals 10 and H carried by insulating panel I0. Bracket 56 also tion with transformer IIJI.

bears a leaf spring 15 extending outwardly therefrom and adapted to abut a post 16 mounted in panel II). A wire 11 leads from contact bearing arm 6I to an associated terminal 16.

From the foregoing it will now be seen that as lever I5 is moved towards the left as seen in Figures 1 and 2 by the pressure of bellows I 2, contact button 62 abuts contact screw 66 and that leaf spring 15, through its abutment with post 16, serves normally to hold the parts in the position described immediately above in the absence of extraneous pressure. Such extraneous pressure, however, is occasioned when, upon a predetermined drop in temperature bellows I2 contracts sufflciently to permit spring 22 to bear upwardly against the head 20 of screw I9 and consequently rotate lever I5 about its fulcrum knife edge I1 to move the end of lever I5 which bears contact finger 31 toward the right, whereupon upwardly extending portion 55 of bell-crank member 5I engages abutment 69 to force the contact bearing member M to the right against the pressure of leaf spring 15 and consequently to engage contact button 63 with contact screw 61. Upon an increase in temperature, bellows I2 expands and spring 15 through engagement with member 6I returns contact 62 to engagement with contact screw 66.

Having now particular reference to Figure 2, it will be seen that wires 90, SI and 92 lead from terminals 19, 10 and II, respectively, to appropriately positioned terminals carried by a valve motor 93. It will also be seen that wires 99, 95 and 96 lead from contacts GI, 33 and 33, respectively, to appropriate contacts carried by a proportioning motor 91 comprising a portion of a unit ventilator, generally indicated at 98. Valve motor 93 is energized through suitable line wires 99 and I00 which lead from step-down transformer IOI which is in turn connected to any suitable source of power (not shown) and serves to actuate a valve I62 associated with the steam supply line I93 of a conventional radiator I 06.

Proportioning motor 91 may be of any desired type although such a motor as disclosed in Patent No. 1,989,972 granted to Lewis L. Cunningham has been found to be well adapted to serve the requisite purpose. Motor 91 is energized through wires I 65 and I06 leading from a stepdown transformer I61 to which power is supplied from any suitable source (not shown) which may be the same source as that referred to in connec- Motor 91 is preferably provided with a lever arm I98 which is in turn operably associated with a plurality of sets of dampers I09 positioned in a passage (not shown) which leads from the exterior to the interior of the space to be heated. The arrangement of these sets of dampers is such that one set controls the admission of fresh air and the other the extrusion of recirculated air and one set opens proportionately as the other set closes. This arrangement is known in the art and forms no portion of the instant invention. A radiator III) also controlled by motor 91 is provided to supply adequate heat to the air passing thereby. It will now be seen, upon consideration of the foregoing, that, assuming the parts to be in the position shown in Figure 2, the temperature requirements of the room are substantially satisfied. Finger 31 is-- held by the previously described action of bellows I2 adjacent a portion of potentiometer coil 39 which provides through proportioning motor 91 a maximum admission of fresh air through dampers I09 and a minimum bit of heat from radiator H0. As the temperature decreases, finger 31 will be moved to the right along coil 30 to provide a constantly decreasing admission of fresh air through dampers H19 an increasing amount of heat from radiator ill) in proportion to the temperature requirements of the space. The theory of proportioning control and the operation of the above mentioned elements is well known and needs no further discussion in connection with the instant invention.

Assume, however, the temperature drops to a point so low that dampers I09 completely preclude the admission of fresh air and unit ventilator 98 is providing substantiallyits full capacity of heat through radiator Hi3, further travel of finger 31 and its associated mechanism including lever i5 and bell-crank member 51 to the right will close contact 636'! to energize valve motor 93 to permit opening of valve in and consequent heating of radiator i6 1. Upon a slight increase in temperature, however, leaf spring 15 will force contact 83 out of engagement with contact screw 81 and place contact 82 in engagement with contact screw 66 which will in. turn serve to energize valve motor 93 to close valve 902 and return full control to unit ventilator 98.

Insulating panel l0 may be secured to a wall or other suitable surface, as by means of mounting screws l is, and a suitable casing (not shown) may be provided to enhance the appearance of the instrument as well as to protect the same from damage.

While there has been herein described an application of the control mechanism of the invention to a unit ventilator and a radiator, it will be readily apparent to those skilled in the art that its uses will be many and varied and the limitation of the application of the device to a system as described is not contemplated.

From the foregoing it will now appear-that there is herein provided a structure which achieves in an efficient and practical manner the objects of this invention including many advantages of great practical importance, such as simplicity of construction, a minimum of working parts, reliability in operation and efficiency in providing adequate control of a heating, or other, installation.

As many possible embodiments may be made of the above invention and as many changes might be made in the embodiment above set forth, it is to be understood that all matter here- :lnbefore set forth or shown in the accompanying drawing isto be interpreted as illustrative and not in a limiting sense.

I claim as my invention:

1. A device of the character described com= prising in combination, a pressure responsive device, a lever actuated by saidpressure responsive device, a resilient arm mounted on one end of said lever, an electrical resistance element, slider mounted on said arm and adapted to slide across said resistance as said lever is moved bacls and forth by said pressure responsive device, a first abutment member carried by said lever, a second pivoted abutment member, a stationary pin, a resilient arm carried by said second abutment member, said last mentioned resilient arm engaging said pin to bias said second abutment member in one direction, said second abutment member being rotated against its bias by said pressure responsive device by means of said first abutment member, and control means actuated by said second abutment member.

2. A device of the character described comprising in combination, a bellows, a lever pivoted intermediate its ends, a bellows abutting said lever on one side of its pivot, a spring engaging said lever on the other side of its pivot and holding it in contact with said bellows whereby expansion and contraction of said bellows will cause said lever to rotate back and forth about its pivot, a resilient arm mounted on said lever, an electrical resistance element, a slider mounted on said arm and adapted to slide over said resistance element as said lever rotates on its pivot, a first abutment member mounted on said lever, means for insulating said abutment member with respect to said lever, 21. second abutment member pivoted independently of said lever, a stationary pin, a resilient arm carried by said second abutment member, said last mentioned resilient arm engaging said pin so as to bias said second abutment member in one direction, means for rotating said second abutment against its bias comprising said first abutment, and an open contact switch actuated by said second abutment.

3. A temperature sensitive device adapted for use in controlling space heaters, comprising in combination, a temperature responsive bellows, a lever actuated by said bellows, a resilient arm mounted on one end of said lever, means for insulating said arm with respect to said lever, an electrical resistance, a slider mounted on said resilient arm and adapted to slide across said resistance as said lever is moved back and forth by said bellows, a first abutment carried by said lever, means for insulating said abutment with respect to said lever, a second abutment pivoted independently of said lever, a stationary member, a resilient arm carried by said second abutment and engaging said stationary member to bias said second abutment in one direction, and control means actuated by said second abutment, said J.

bellows responding to temperature which is changing in one direction to first move said slider across said resistance and thereafter cause said first abutment to engage and move said second abutment against its bias to actuate said control means.

4. A temperature sensitive device adapted for use in controlling space heaters, comprising in combination, a temperature responsive bellows, a lever actuated by said bellows, a resilient arm mounted on one end of said lever, means for insulating said arm with respect to said lever, an electrical resistance, 'a slider mounted on said resilient arm and adapted to slide across said resistance as said lever is moved back and forth by said bellows, a first abutment carried by said lever, means for insulating said abutment with respect to said lever, a second abutment pivoted independently of said lever, a pair of spaced stationary contacts, a movable contact carried by said second abutment between said stationary contacts, a stationary pin, and a resilient arm carried by said second abutment engaging said pin and biasing said movable contact into en-= gagement with one of said stationary contacts, said bellows in responding to a temperature change in one direction first causing said slider to slide across said resistance and then causing said first abutment to engage said second abutment to rotate it against its bias and cause said movable contact to disengage said one stationary contact and engage said other stationary contact.

DANIEL G. TAYLOR. 

